Increasing the spontaneity of an automatic gear box

ABSTRACT

For an electro-hydraulically controlled automatic transmission (2) in which shifts are performed by overlapping, a method is proposed for increasing the spontaneity, in which a variable hold time is introduced for a disengaging clutch. This variable hold time is a function of the rotational speed differential of a transmission input speed (nT) and the temperature of the hydraulic fluid (Θ).

This invention concerns a method for increasing the spontaneity of anelectrohydraulically controlled automatic transmission in which agearshift from a first reduction step to a second reduction step in adownshift is effected by a first clutch opening and a second clutchclosing.

BACKGROUND OF THE INVENTION

In automatic transmissions, gearshifts are usually overlappinggearshifts, that is, a first clutch opens and a second clutch closes.Thus, U.S. Pat. No. 5,079,970, for example, proposes an overlappinggearshift for a downshift wherein, at the beginning of the shift, thepressure level applied to the first clutch is reduced to a lowerpressure level according to a ramp function. This is followed by a timefunction during which the transmission input speed increases. Thepressure curve of the second engaging clutch, consists of rapid filling,filling equalization and a load take-up phase. Downshifts are usuallyproduced when an presettable accelerator pedal value exceeds a downshiftcharacteristic line. Together with downshifts produced by means of theaccelerator pedal, the driver also has the possibility of producingmanual downshifts whenever desired. DE-OS 43 11 886, for example, showsa device by which with the aid of a selector lever the driver canproduce gearshifts with a manual gate or shifting rocker on a steeringwheel. For manually produced downshifts, for example, there arises, inpractice, a problem of long reaction times, that is, the time interval,from the manual demanded downshift, until a noticeable reaction of theautomatic transmission appears. Long reaction times result from the idletimes of the signals controlling the hydraulic system, blocking timesbetween two consecutive gearshifts and the time needed for thedisengagement of the first clutch or filling of the second clutch. Thelong reaction times are felt as unpleasant by the driver.

The invention is based on the problem of improving the spontaneity ofthe automatic transmission, specially in a downshift and a double shiftincluded therein.

SUMMARY OF THE INVENTION

According to the invention, the problem is solved by reducing, with theissuance of the shift command, the pressure level of the first clutchfrom a first pressure level to a second pressure level and maintainingthe second pressure level during a hold time, this being a function of arotational speed differential of a transmission input speed and thetemperature of the hydraulic fluid. With the termination of the holdtime, the pressure level of the first clutch is reduced to a thirdpressure level for a recovery time. This third pressure level determinesthe recovery time curve of the transmission as the pressure level of thefirst clutch is reduced to zero. The solution, according to theinvention, offers the advantage of a variable hold time. The reactiontime is determined by said hold time. Preferably, the hold time ispatterned in such a manner that a small speed jump of the transmissioninput speed a long hold time is provided and in a large jump of thetransmission input speed a very short hold time is spent.

Preferably, the speed jump of the transmission input speed is calculatedfrom the transmission input speed at the beginning of the gearshift inthe first reduction step and the value of the transmission input speedat the synchronization point of the second reduction step.

For applying the method to sequentially performed double shifts, it isfurther proposed, according to the invention, that in double shiftscomprising a first shift and a second shift, the second shiftcorresponds to a downshift, the change for the second shift as describedabove.

In a development of this, it is proposed that in a double shift in whichthe first shift corresponds to an upshift from a first to a secondreduction step, a time step be started with disengagement of the firstclutch. Said time step extending up to a maximum time wherein areduction time is associated with each value of the time step. Thereduction time in that case determines a rapid filling time of theengaging clutch in the downshift. This solution offers the advantagethat blocking periods between the upshift and the downshift areeliminated. Said blocking periods were needed, because the disengagingclutch in the upshift is filled again in the downshift that follows sothat a reliable draining had to be previously guaranteed.

BRIEF DESCRIPTION OF THE DRAWINGS

One embodiment is illustrated in the drawings which show:

FIG. 1 is a system table of an automatic transmission;

FIGS. 2A-2D are time diagrams for a downshift; and

FIGS. 3A-3G and FIGS. 4A-4D are time diagrams for a double shift.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a system table of an automatic transmission. The automatictransmission 2 consists of one hydrodynamic converter 7, a compositeplanetary transmission 11 with differential 12, a hydraulic controldevice 4 and an electronic transmission control 5. An internalcombustion engine 1 drives the automatic transmission 2 via an inputshaft 6. An electronic engine control device 3 controls or regulates theinternal combustion engine 1. The input shaft 6 is non-rotatablyconnected with the hydrodynamic converter 7 and drives the impeller 8thereof. As already known, the hydrodynamic converter 7 comprises theimpeller 8, a turbine wheel 9 and a stator 10. Parallel to thehydrodynamic converter 7 is shown without reference numeral a converterlock-up clutch. When the converter lock-up clutch is actuated, theturbine shaft rotates at the same speed as the input shaft 6. Thecomposite planetary transmission 11 consists of two pairs of planetgears and the clutches and brakes B to F. The output takes place via thedifferential 12 and the two axle half shafts 13A and 13B. Since themechanical part is not relevant for better understanding of theinvention, a detailed description is omitted. The clutches and brakes Bto F are controlled or regulated by the electronic transmission control5 via the hydraulic control device 4. The shifts, that is, the upshiftsand downshifts of the automatic transmission 2, are effected asoverlapping shifts in which a first clutch opens and a second clutchcloses. In the hydraulic control device 4 are placed electromagneticactuators and hydraulic shift valves. Of the electronic control device5, there are shown, in extensively simplified form, the function blocksof a micro-controller 14, memory 15, function block control elements 16and function block calculator 17. The memory 15 is usually designed asan EPROM, EEPROM, or as buffered RAM. In the memory 15 are deposited thedata relevant to the transmission. The function block control element 16serves to control the electromagnetic control elements in the hydrauliccontrol device 4. The function block calculator 17 serves to calculatethe data relevant to the shift. These are determined from the inputparameters 18 to 21. Input parameters 20 are, for example, the signal ofa selector lever, the signal of tipping keys, the speed of the internalcombustion engine, the signal of the position of an accelerator pedal orthrottle valve, the temperature of the hydraulic fluid, etc. Theelectronic motor control device 3 and the electronic control device 5are interconnected by a data line 21. Said data line 21 can be designedas an unidirectional wire intersection point, for example, to carry outa motor gearing. The data line 21 can also be designed as bi-directionaldata line for a bus system such as CAN bus. Added input parameters forthe control device 5 are the transmission input speed 18, that is, thespeed of the turbines shaft, and the transmission output speed 19.

FIG. 2 consists of the parts FIGS. 2A to 2D. A shift from a first to asecond reduction step to downshift is shown. The figures respectivelyshow in the course of time: FIG. 2A a state diagram of the shiftcommand, FIG. 2B a speed curve nT of the transmission input speed, FIG.2C a pressure curve pK1 of a first, the disengaging, clutch and FIG. 2Dthe pressure curve pK2 of a second, the engaging, clutch. Two examplesare shown in FIGS. 2B, 2C and 2D. FIG. 2B shows, with reference numeral22, a downshift beginning at low speed level. To said first examplebelongs in FIG. 2C, with reference numeral 24, the pressure curve pK1 ofthe first clutch and in FIG. 2D, with reference numeral 26, the pressurecurve pK2 of the second clutch. To the second example in FIG. 2B, withreference numeral 23, belongs in FIG. 2C the pressure curve pK1 of thefirst clutch, with reference numeral 25, and in FIG. 2D the pressurecurve pK2 of the second clutch, with reference numeral 27.

FIRST EXAMPLE

At the moment t1, a shift command is issued, that is, in FIG. 2A thestate of the signal changes from one to zero. With issuance of the shiftcommand, the pressure level pK1 of the first clutch changes from a firstpressure level p1 toward a pressure level p2. Also at the moment t1, thesecond clutch is loaded with a high pressure level p5, the rapid fillingpressure. This terminates at the moment t3. Thereafter the second clutchis charged with filling pressure p6. At the moment t4 terminates a holdtime of the first clutch which begins at the moment t1. Aftertermination of the hold time at the moment t4, the pressure level pK1 ofthe first clutch is reduced from the second pressure level p2 to a thirdpressure level p3. Hereby changes the curve of the input speed nT. Atthe moment t6, the transmission input speed nT has reached thesynchronization point. At the synchronization point, the second clutchtakes over the load from the first clutch, that is, the pressure levelof the first clutch is reduced to zero while the pressure level of thesecond clutch is raised from the filling pressure to the value p4. Atthe moment t7, the shift is terminated, that is, the pressure level pK2of the second clutch goes to a pressure level following the shift.

SECOND EXAMPLE

At the moment t1, the shift command is issued, the signal changes inFIG. 2A from one to zero. The pressure level of the first clutch pK1simultaneously is reduced from a first level p1 to a second level p2.Also at the moment t1, the second clutch is loaded with the rapidfilling pressure p5. The rapid filling pressure is maintained up to themoment t3, then the second clutch is charged with filling pressure. Atthe moment t2, the hold time of the first clutch has expired. With theend of the hold time, the pressure level pK1 of the first clutch ispassed from the second pressure level p2 to a third pressure level p3.As consequence of this the curve of the transmission input speed nT ofFIG. 2B changes. At the moment t5 is reached the synchronous speed ofthe new gear. In FIG. 2B said synchronous speed value is designated asnT(2) on the ordinate. At the synchronization point the second clutchtakes over the load from the first clutch. The pressure level pK1 of thefirst clutch is thus reduced to zero while the pressure level of thesecond clutch pK2 is raised to the pressure level p4. At the moment t7,the pressure level pK2 of the second clutch changes to a pressure levelfollowing the shift.

In the first example, the hold time lasts from t1 to t4. In the secondexample, the hold time lasts from t1 to t2. Said hold time is variablyrealized. Input parameters of said hold time are a rotational speeddifferential d₋₋ nT of the transmission input speed nT and a temperatureof the hydraulic fluid Θ so that tHALT=f(d₋₋ nT, Θ) applies. Therotational speed differential d₋₋ nT results from the difference of thetransmission input speed in the first and second synchronization points.For the second example thus results the rotational speed differential:d₋₋ nT=nT(2)-nT(1).

In a simpler embodiment, the hold time can also be alternativelydetermined depending only on the transmission input speed in the firstsynchronization point nT(1) or in the second synchronization pointnT(2). Thus applies:

    tHALT=f(nT(1), Θ

or

    tHALT=f(nT(2), Θ).

As shown in FIG. 2, there thus results for the Example 2 compared toExample 1 a time advantage of Δt. The effect of this time advantage isthat a driver, after having induced a downshift, perceives more quicklya reaction of the automatic transmission; in other words: he feels morespontaneously the behavior of the automatic transmission.

FIG. 3 shows an application to a double shift of the method described inFIG. 2. Said double shift consists of a first and second sequentiallyperformed shifts. Both the first and the second shifts are downshifts,that is, for a ex., a double shift from the fifth to the third gear.FIG. 3 consists of the parts FIG. 3A to 3G. They respectively show inthe course of time:

FIG. 3A the driver's desired performance FW;

FIG. 3B the shift command SB;

FIG. 3C the curve of the transmission input speed nT in two examples(reference numerals 28, 29);

FIG. 3D the pressure curve pK1 of the two first, that is, disengaging,clutches for the first example:

FIG. 3E the pressure curve pK2 of the two second, that is, engaging,clutches for the first example;

FIG. 3F the pressure curve pK1A for both first clutches of the secondexample; and

FIG. 3G the pressure curve pK2A for both first clutches of the secondexample.

FIG. 3C shows, with reference numeral 28, a first example of a doubleshift according to the prior art. The pressure curves of FIGS. 3D and 3Ebelong to said speed curve nT. As detected, a total of four clutchestake part in this double downshift. A second example is shown in FIG.3C, with reference numeral 29. This example corresponds to the solutionaccording to the invention. The pressure curves of FIGS. 3F and FIG. 3Gbelong to the speed curve nT according to reference numeral 29.

FIRST EXAMPLE

At the moment t1, a driver issues a wish for a first downshift. Therebythe signal curve changes in FIGS. 3A and 3B. The pressure level pK1 ofthe first clutch of the first downshift, reference numeral 30, issimultaneously reduced to the second pressure level p2. The latter ismaintained during the hold time, that is, the time interval t1 to t3.Also at the moment t1, the second clutch, reference numeral 32, isloaded with the rapid filling pressure p5. The rapid filling pressurelasts up to the moment t2. Thereafter the second clutch is filled withthe filling pressure p6. At the moment t3, the hold time has expired,that is, the pressure level pK1 of the first clutch is reduced from thesecond pressure level p2 to the third pressure level p3. Thereby changesthe curve of the transmission input speed nT from nT(1) in direction tonT(2). The gradient of the transmission input speed can be determined bythe pressure level p3 of the first clutch. At the moment t4, thesynchronous speed value nT(2) is reached. At the synchronization point,the pressure level pK2 of the second clutch has reached the pressurelevel p4. Since the second clutch has now taken over the load from thefirst clutch, the pressure level p3 of the first clutch is reduced tozero. It is now assumed that in the time interval t2 to t4 the driverhas brought about a second downshift. This is shown in FIG. 3A by thesignal level of the driver's wish FW changing from "4" to "3". At themoment t4, with the detection of the synchronization point nT(2), a newshift command is thus issued, as can be seen in FIG. 3B. Also at themoment t4, the pressure level pK1 of the second disengaging clutch isreduced from the pressure level p1 to the pressure level p2. Thepressure level pK2 of the second engaging clutch is simultaneouslybrought to the rapid filling pressure level p5 for the during t4 to t5.Thereafter the second engaging clutch is filled with the fillingpressure p6. The hold time of the first clutch, reference numeral 31,runs during the time interval t4 to t6. During this hold time, the curveof the transmission input speed nT does not change, that is, the speedremains static during the speed value nT(2). At the moment t6, the holdtime has expired, that is, the pressure level pK1 of the first clutch isreduced from the second pressure level p2 to the third pressure levelp3. Hereby the curve of the transmission input speed nT change from thevalue nT(2) in direction to nT(3). At the moment t7 is reached, thesynchronization point, speed value nT(3) in FIG. 3C. At thesynchronization point, the second engaging clutch, according to FIG. 3E,takes over the load from the first clutch. The first clutch issimultaneously passed from the third pressure level p3 to zero.

SECOND EXAMPLE

The second example shows the solution according to the invention. Thesecond example comprises in FIG. 3C, in the speed curve of thetransmission input speed nT, according to reference numeral 29, thepressure curves of the two disengaging clutches, reference numerals 34and 35 in FIG. 3F and the pressure curves of the two engaging clutches,reference numerals 36 and 37 in FIG. 3G. At the moment t1, a driverinitiates a downshift, for ex., from the fifth to the fourth gear, asshown in FIG. 3A. Thereby a shift command is issued, see FIG. 3B. At themoment t1, the pressure level pK1A of the first disengaging clutch,reference numeral 34, is reduced from the first pressure level p1 to thethird pressure level p3. In the instant example, it has thus beenassumed that the hold time has been calculated as zero. The hold time isa function of the rotational speed differential of the transmissioninput speed d₋₋ nT and of the temperature Θ of the hydraulic medium. Thedifference of the two synchronization points nT(2) and nT(1). As soon asthe pressure level pK1A of the first disengaging clutch has reached thethird pressure level p3, the gradient of the transmission input speed nTchanges in direction to the speed value nT(2). The pressure value p3 ismaintained up to the moment t2A. The curve of the transmission inputspeed is determined by the pressure level p3. Also at the moment t1, thefirst engaging clutch, reference numeral 36, is loaded with rapidfilling pressure, pressure level p5, up to the moment t2. Thereaftersaid clutch is filled with the filling pressure p6. At the moment t2A,the synchronous speed nT(2) is reached. At this point, the firstengaging clutch takes over the load from the first disengaging clutch.The pressure level of the first disengaging clutch is reduced from thethird pressure level p3 to zero. Simultaneously with the detection ofthe synchronous speed nT(2), the second disengaging clutch, referencenumeral 35, is reduced from the first pressure level p1 to the thirdpressure level p3. The hold time is here eliminated, since it has beencalculated as zero. Thereafter follows with pressure level p3 thecontrol phase during which the curve of the transmission input speedchanges in direction nT(3). Also at the moment t2A, the second engagingclutch, reference numeral 37, is loaded with rapid filling pressurefollowed by filling pressure p6. At the moment t4, the secondsynchronization point nT(3) is reached. At said synchronous speed valuethe second engaging clutch takes over the load from the seconddisengaging clutch. The second disengaging clutch is reduced from thethird pressure level p3 to zero. As it can be seen from FIGS. 3A and 3B,as result of the driver's demand for one other downshift, moment t2A,the shift command is immediately issued. As shown in FIG. 3C, there thusresults for both examples a time offset Δt from the moment t4 up to themoment t7; in other words: compared to the speed curve, according to theprior art, reference numeral 28, the application of the method of theinvention results in the speed curve according to reference numeral 29.Between the driver's demand for a double downshift and the reaching ofthe synchronous speed value nT(3), a short time thus elapses accordingto the curve reference numeral 29, that is, the reaction time wasclearly shortened; the driver perceives a spontaneous reaction.

In FIG. 4 is shown a double shift comprising an upshift and a downshiftthat follows it. A typical example from the practice would be when adriver drives behind a truck and intends to overtake. In view of thetraffic in opposite direction, he reduces the position of theaccelerator pedal so that the automatic transmission upshifts, for ex.,from the fourth to the fifth gear. During the upshift the driver detectsthat the opposite road is now free and again actuates the acceleratorpedal. According to the prior art in this case, the upshift is firstentirely carried out. Thereafter usually comes a blocking time and onlythen is begun the downshift from the fifth to the fourth gear. Theblocking time is thus needed, since it must be ensured that thedisengaging clutch be completely drained in the upshift. If this is notthe case, the rapid filling of the now engaging clutch during thedownshift makes itself noticeable in the form of a jolt. FIG. 4 consistsof parts FIGS. 4A to 4D. They respectively show in the course of time:

FIG. 4A the shift command;

FIG. 4B the speed curve of the transmission input speed nT;

FIG. 4C the pressure curve of a first clutch; and

FIG. 4D the pressure curve of a second clutch.

Two examples are again shown in FIG. 4B. The speed curve with thereference numeral 40 corresponds here to a solution according to theprior art. To this speed curve belongs, with the reference numeral 38,the issuance of the shift command in FIG. 4A, the pressure curve of thefirst clutch according to reference numeral 42 and the pressure curve ofthe second clutch in FIG. 4D, with reference numeral 44. The secondexample in FIG. 4B, with reference numeral 41, shows a speed curve nTaccording to the invention. To said speed curve belongs in FIG. 4A,reference numeral 39, the shift command, in FIG. 4C the pressure curveof the first clutch, with reference numeral 43, and the pressure curveof the second clutch in FIG. 4D, with reference numeral 45. At themoment t1 is issued a shift command to upshift. The first clutch issimultaneously charged with the rapid filling pressure, pressure levelp4, for the time interval t1 to t2. In the time interval t2 to t3, theclutch is then charged with filling pressure, pressure level p6.Thereafter follows for the time interval t3 to t6 a pressure increaseaccording to straightening function. The terminal point is here thepressure level p3. Also at the moment t1, the pressure level of thesecond clutch is reduced from the value p7 to pressure level p8. Saidpressure level is maintained up to the moment t4. Since in the timeinterval t3 to t5, the first clutch begins to take over the load fromthe second clutch, the second clutch can be disengaged at the moment t4.As consequence of the load assumption, the transmission input speed nTbegins to change from the synchronization point nT(1) in direction tothe new synchronization point nT(2). At the moment t6, the speed valuenT(2) is reached, the upshift is thus terminated. Thereafter thepressure level of the first clutch is raised to the pressure level p1.If during the upshift, time interval t1 to t6, the driver actuates theaccelerator pedal and wishes a downshift, then, according to the priorart, a blocking time extends first from the time interval t6 to t7. Notuntil the moment t7 is given the shift command for downshift, referencenumeral 38 in FIG. 4A. Thereby the pressure level of the first clutch isreduced from p1 to p2. This pressure level maintained for the hold time,time interval t7 to t10. At the moment t10, the pressure level of thefirst clutch is reduced from p2 to p5. Thereby the curve of thetransmission input speed nT changes in direction to a new synchronousspeed point nT(1). Also at moment t10, the second clutch is loaded withthe rapid filling pressure, pressure level p10, followed by fillingpressure with the pressure level p1. At the moment t12, the synchronousspeed value nT(1) is reached. At the synchronization point, the secondclutch takes over the load from the first clutch. The first clutch canthus be reduced from the pressure level p5 to zero.

SECOND EXAMPLE

The method, according to the invention, develops identically as abovedescribed up to the moment t6. But at the moment t4, a time step isstarted with the disengagement of the second clutch. This time stepextends up to a maximum end value tMAX, for ex., 2 minutes. With eachtime value is here associated a reduction time by which the rapidfilling time is reduced. Thus results, for ex., in a time value of 100msec a reduction time of -50 msec, or in a time value of 200 msec areduction time of zero. Between said values is linearly interpolated.One other variant for calculating the rapid filling time can be carriedout as follows: With each time value of the time step a rapid fillingtime is associated. Said rapid filling time is added to a basic rapidfilling time; for ex., the basic rapid filling time can amount to 20msec. When 60 msec result from the time step, the final rapid fillingtime is thus calculated to be 80 msec. At the moment t6 is issued, therepeated shift command for the downshift, reference numeral 39 in FIG.4A. The effect of this is that the pressure level of the first clutch isreduced to the pressure level p5. Thus, the hold time was calculated aszero in this case. Also at the same time, the second clutch is filledwith rapid filling pressure, pressure level p10. The time interval forthe rapid filling, here t6 to t6A, is function of the values of the timestep. This means in the practice that lesser values of the time stepresult in a short rapid filling time. In the extreme case, the rapidfiling time can also be zero when it is specifically detected on thebasis of the time step that the disengaging clutch still has not beendrained. In the time interval t6 to t9, the second clutch is loaded withfilling pressure p11. At the moment t9, the synchronous speed valuenT(1) has been reached and the pressure level of the second clutch israised to the value p9 so that it can reliably take over the load fromthe first clutch. Also at the moment t9, the first clutch, referencenumeral 43, is reduced to zero. At the moment t12, the shift terminates,that is, the pressure level of the second clutch is reduced to thepressure level beyond the shift. As down in FIG. 4B, when using themethod according to the invention, a time advantage Δt, time interval t9to t12, results in comparison with the method according to the priorart, reference numeral 40. In other words: After an upshift thedownshift is immediately performed without time offset. When overtaking,a very short time passes between the driver's wish and the actualacceleration, the spontaneity of the transmission being thus increased.

What is claimed is:
 1. A method for increasing the spontaneity of anelectro-hydraulically controlled automatic transmission (2) in which ashift from a first reduction step to a second reduction step indirection to a downshift is effected by a first clutch opening and asecond clutch closing, an electronic transmission control (5) whichcontrols, via electromagnetic elements, operating pressure curve of thefirst and second clutch, wherein with the issuance of a shift commandthe pressure level of the first clutch is reduced from a first pressurelevel (p1) to a second pressure level (p2), said second pressure level(p2) being maintained during a hold time (tHALT) wherein the hold time(tHALT) is a function of a rotational speed differential (d₋₋ nT) of atransmission input speed (nT) and hydraulic fluid temperature (Θ)(tHALT=f(d₋₋ nT, Θ), with the expiration of said hold time (tHALT=zero),the pressure level of said first clutch is reduced to a third pressurelevel (p3) for a recovery time (tRECOV), said third pressure level (p3)determining here the transmission input speed (nT) and with theexpiration of said recovery time (tRECOV=zero), the pressure level ofsaid first clutch is reduced to zero.
 2. The method according to claim1, wherein said hold time becomes approximately zero where a highrotational speed differential (d₋₋ nT) results from said transmissioninput speed (nT).
 3. The method according to claim 2, wherein saidrotational speed differential (d₋₋ nT) is calculated from the value oftransmission input speed at the beginning of a shift (nT (1)) in a firstreduction step and from the value of transmission input speed at thesynchronization point of a second reduction step (nT (2)) whereby theequation: d₋₋ nT=nT(2)-nT(1) applies.
 4. The method according to claim1, wherein double shifts are sequentially carried out in the form of afirst and a second shift and the second shift is a downshift effectedaccording to claim
 1. 5. The method according to claim 4, wherein in thedouble shift, the first shift of which is a downshift from a first to asecond reduction step, with the disengagement of said first clutch atime step (tR) is started which extends up to a maximum time (tMAX), areduction time being associated with each value of said time step (tR).6. The method according to claim 5, wherein a rapid filling time (tSF)of said first engaging clutch in the downshift is changed according tothe reduction time.
 7. The method according to claim 6, wherein therapid filling time changes in the sense that a lesser value of the timestep (tR) causes a short rapid filling time (tSF).
 8. The methodaccording to claim 1, wherein said hold time (tHALT) is calculated aszero (tHALT=0) when the rotational speed differential (d₋₋ nT) of thetransmission input speed (nT) exceeds (d₋₋ nT>GW) a limit value (GW). 9.A method for increasing the spontaneity of an electro-hydraulicallycontrolled automatic transmission (2) comprising the stepsof:downshifting from a shift from a first reduction step to a secondreduction step, the downshift is effected by a first clutch opening anda second clutch closing; controlling an operating pressure level of thefirst and second clutch via electromagnetic elements of an electronictransmission control (5); issuing a shift command wherein the pressurelevel of the first clutch is reduced from a first pressure level (p1) toa second pressure level (p2); maintaining said second pressure level(p2) during a hold time (tHALT) wherein the hold time (tHALT) is afunction of a rotational speed differential (d₋₋ nT) of a transmissioninput speed (nT) and hydraulic fluid temperature (Θ) (tHALT=f(d₋₋ nT,Θ); reducing the pressure level of said first clutch, upon expiration ofsaid hold time (tHALT=zero), to a third pressure level (p3) for arecovery time (tRECOV); determining the transmission input speed (nT),and with the expiration of said recovery time (tRECOV=zero), reducingthe pressure level of said first clutch to zero; sequentially carryingout the double shift comprising a first and a second shift, wherein oneof the first and second shift is the downshift from the first to thesecond reduction step, and upon the disengagement of said first clutch atime step (tR) is started which extends up to a maximum time (tMAX), areduction time being associated with each value of said time step (tR);and changing a rapid filling time (tSF) of said first engaging clutch inthe downshift according to the reduction time.
 10. A method forincreasing the spontaneity of an electro-hydraulically controlledautomatic transmission (2) comprising the steps of:downshifting from ashift from a first reduction step to a second reduction step, thedownshift is effected by a first clutch opening and a second clutchclosing; controlling an operating pressure level of the first and secondclutch via electromagnetic elements of an electronic transmissioncontrol (5); issuing a shift command wherein the pressure level of thefirst clutch is reduced from a first pressure level (p1) to a secondpressure level (p2); maintaining said second pressure level (p2) duringa hold time (tHALT) wherein the hold time (tHALT) is a function of arotational speed differential (d₋₋ nT) of a transmission input speed(nT) and hydraulic fluid temperature (Θ) (tHALT=f(d₋₋ nT, Θ); reducingthe pressure level of said first clutch, upon expiration of said holdtime (tHALT=zero), to a third pressure level (p3) for a recovery time(tRECOV); determining the transmission input speed (nT), and with theexpiration of said recovery time (tRECOV=zero), reducing the pressurelevel of said first clutch to zero; calculating said hold time (tHALT)as zero (tHALT=0) when the rotational speed differential (d₋₋ nT) of thetransmission input speed (nT) exceeds (d₋₋ nT>GW) a limit value (GW).